In order to obtain cut-off beams with optical modules having a lens, of the elliptical module type, shields can be inserted into the module in front of the lens in the path of light rays coming from the light source. The shield, which is of an appropriate form, may be fixed: the module is then a single-function module. It may also be movable, so that the module is then a two-function or multi-function module, and so that there can be obtained, with a single module, a beam of the low beam type (with the shield in a working position intercepting some of the light rays), and a beam of the cruising type (with the shield put into an inactive position), or, in an example of a triple function, a cruising type beam (with the shield in an inactive position), a low beam for left-hand drive (with the shield in an active position 1), and a low beam for right-hand drive (with the shield in an active position 2). Numerous patents describe this type of module, both single function and multi-function, for example patents EP1197387 and EP1422472.
In order to obtain cut-off beams, while at the same time giving overhead light with this type of optical module with a lens, a first solution was proposed in the patent EP 1 464 890. It disclosed the use of a shield which was adapted to effect ad hoc cut-off, and a lens provided with peripheral arrangements which are capable of deflecting upwards the light rays that reach them in such a way that enough light reaches the overhead points concerned. In this connection, these overhead target points are normally in a high zone of vision where the light coming from the optical module is occulted by the shield. The said arrangements are for example in the form of ribs located on the lower periphery of the lens. That solution is quite effective from the optical point of view, because the ribs in the lower part effectively enable a little light to be deflected upwards, and above the cut-off line, towards the road signs without significantly disturbing the photometry and distribution of the main cut-off beam. However, the said arrangements may be seen as a disadvantage from the styling point of view, because they remain visible even though they are located at the periphery of the lens.
The invention therefore has the object of providing a new type of lens which enables a beam to be obtained having a particular photometry, and being in particular of the cut-off type with overhead lighting, with optical modules of the elliptical type having a lens which can overcome the above disadvantage. In particular, an object of the invention is to obtain a lens which performs at least as well from the optical point of view, but which has an appearance, once it is fitted in the module, that is as close as possible to that of a standard lens.